Accurate analysis of MMI devices with two-dimensional confinement

The accurate analysis of multimode interference (MMI) devices with two-dimensional (2-D) confinement has been demonstrated by using the least squares boundary residual (LSBR) method. Accurate modal propagation constants and spatial field profiles in the MMI section are obtained by using the vector H-field based finite element method. The accurate calculation of the excited modal coefficients is achieved by using the LSBR, which satisfies the continuity of the transverse field components more rigorously than using simple overlap integrals     

Review of finite-element characterization of photonic devices

Abstract

We report the development and applications of finite-element-based numerical approaches for the characterization of a wide range of photonic devices. The full-vectorial finite-element method is considered for the modal solutions of uniform guided-wave sections and the least-squares boundary residual method is used to calculate the scattering coefficients for butt-coupled uniform waveguide sections. Several guided-wave components are discussed and their operating characteristics are illustrated. Particular emphasis is given to key photonic components such as the spot-size converters, Bragg gratings, polarization splitters, polarization rotators, multimode interference-based devices and modulators. Valuable results relating to the design and characterization of these important photonic components are presented.     

Spot-size conversion using uniform waveguide sections for efficientlaser-fiber coupling

Using numerically simulated results, it is shown that an efficient laser-to-fiber coupling is possible by incorporating a uniform spot-size converter (SSC) with two nonidentical but phase matched optical waveguides. Using a “diluted” waveguide with a low index contrast, the power coupling loss can be significantly reduced from 10.4 dB to only 1.15 dB and at the same time 1.0 dB alignment tolerances can also be improved to achieve ±1.8 μm. Besides the improved coupling, the beam divergence of the far-field is also reduced considerably to 9°, accompanied by a significant lowering of the reflected power from the fiber interface     

Accurate analysis of multimode interference devices

The accurate analysis of multimode interference devices is demonstrated by using the least-squares boundary residual (LSBR) method. Accurate modal propagation constants and spatial field profiles in the multimode interference (MMI) section can be obtained by using the finite-element method. The accurate calculation of the excited modal coefficients is achieved by using the LSBR, which satisfies the continuity of the transverse field components more rigorously than the simple overlap integrals.